Tomographic imaging of fluid flows by the use of two-tone frequency-modulation spectroscopy

Kauranen, P.; Hertz, Hans M.; Svanberg, Sune

doi:10.1364/ol.19.001489

Cited by 23 publications

(13 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Local dispersions in fixed beds are commonly measured by multiple experiments where invasive probes are placed at different locations to collect different residence time distributions [1][2][3][4]. Recent developments of spatially resolved techniques based on magnetic resonance imaging (MRI) [5][6][7], X-ray [8], neutron [9], and laser spectroscopy [10,11] imaging have allowed non-intrusive measurements of anisotropic flow structure, voidage, solid velocity and dispersions in liquid-solid reactors and have achieved rapid access to scalar data of chemical kinetics and associated mass transfer in a single experiment. Unfortunately, these techniques are still not sufficiently mature to be applied to gas-solid reactors due to the inherently weak signal retrieved from the gaseous phase.…”

Section: Introductionmentioning

confidence: 99%

“…For instances, Kauranen et al [11] have reported the measurement of a stationary gas flow with a low O 2 concentration field using a two-tone frequency modulation method, Hindle et al [12] used fibre optics based tomography to observe spatial distributions of hydrocarbon species in a combustion chamber, Salem et al [13] observed water breakthrough in a packed bed adsorber by a fine bandwidth laser, and Reinke et al [14] coupled two spectroscopic techniques of Raman and laser-induced fluorescence to observe spatial profiles of stable and radical species of catalytic partial oxidation of methane between two catalytic plates accessible by lateral transparent windows. In this work, an experimental procedure based on spatially resolved near-infrared (NIR) imaging is developed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Screening wall effects of a thin fluidized bed by near-infrared imaging

Aiouache

tSaoir

Kitagawa

2011

Chemical Engineering Journal

View full text Add to dashboard Cite

a b s t r a c tNear-infrared (NIR) imaging was used to observe water vapour flow in a gas-solid fluidized bed reactor. The technique consisted of a broadband light, an optical filter with a bandwidth centred on strong water vapour absorptions, a Vidicon NIR camera, a nozzle from which an optically active mixture of gas and water vapour was trans-illuminated by an NIR beam and collected data of transmittance were normalized to actual optical path. The procedure was applied to a thin fluidized bed reactor with a low aspect ratio of tube to particle diameters (D t /d p ) in order to validate the wall effect on flow dynamics and mass transfer during the reduction of ceria-silica by hydrogen. High concentrations of water vapour emerged in the vicinity of the wall when the bed was operated at pseudo-static conditions but disappeared when the bed was run at minimum bubbling conditions. This result shows the capability of optical methods with affordable costs to 2D imaging opaque packed bed by using a spatially resolved probe located at the exit, which is of great benefit for in situ visualization of anisotropic concentrations in packed beds under industrially relevant conditions and thus for elucidation of the underlying reaction mechanism and diffusion interactions.Crown

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Screening wall effects of a thin fluidized bed by near-infrared imaging

Aiouache

tSaoir

Kitagawa

2011

Chemical Engineering Journal

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5][6][7][8] Applying TTFMS for quantitative measurements over a wide range of concentrations, temperatures, or pressures requires information about the line parameters and an adequate theory of the heterodyne detected signal. The line parameter data can be found with varying accuracy in the literature and in databases.…”

Section: Introductionmentioning

confidence: 99%

Two-tone frequency-modulation spectroscopy for quantitative measurements of gaseous species: theoretical, numerical, and experimental investigation of line shapes

Avetisov

Kauranen

1996

Appl. Opt.

View full text Add to dashboard Cite

“…[1][2][3][4][5][6] The interaction between a modulated laser field and an absorbing sample leads to the generation of an absorption-related signal that can be detected at the applied modulation, at an overtone, or at an intermediate frequency by use of frequency-and phase-sensitive electronics. Characteristically this process shifts the detection band to a high-frequency region, where the laser excess ͑1͞f ͒ noise is avoided.…”

Section: Introductionmentioning

confidence: 99%

Frequency-modulation spectroscopy with blue diode lasers

et al. 2000

Self Cite

View full text Add to dashboard Cite

Frequency-modulation spectroscopy provides ultrasensitive absorption measurements. The technique is especially adaptable to diode lasers, which can be modulated easily, and has been used extensively in the near-infrared and infrared spectral regions. The availability of blue diode lasers now means that the accessible wavelength region can be increased. We successfully demonstrate wavelength-modulation spectroscopy and two-tone frequency-modulation spectroscopy for the weak second resonance line of potassium at 404.8 nm and for the transition at 405.8 nm in lead, starting from the thermally populated 6p 2 3 P 2 metastable level. Information on the modulation parameters is obtained with a fitting procedure. Experimental signal-to-noise ratios at different absorption levels are compared with theoretical signal-to-noise ratios and show good agreement. Detection sensitivities of 2 ϫ 10 Ϫ6 and 5 ϫ 10 Ϫ6 for wavelength and two-tone frequency-modulation spectroscopy, respectively, for a 120-Hz bandwidth are demonstrated.

show abstract

Tomographic imaging of fluid flows by the use of two-tone frequency-modulation spectroscopy

Cited by 23 publications

References 17 publications

Screening wall effects of a thin fluidized bed by near-infrared imaging

Screening wall effects of a thin fluidized bed by near-infrared imaging

Two-tone frequency-modulation spectroscopy for quantitative measurements of gaseous species: theoretical, numerical, and experimental investigation of line shapes

Frequency-modulation spectroscopy with blue diode lasers

Contact Info

Product

Resources

About